Various types of lifting or hoisting devices are well known in the prior art and include hoists and jacks, which may be used in combination with various scaffolds and/or platform mechanisms. Hoisting devices are used when an object to be moved is either too heavy or bulky to be relocated by human power alone. Many hoisting devices exist which are capable of lifting and moving heavy or bulky objects throughout easily accessible areas, such as warehouses, garages or construction sites. Typically, an object in a warehouse, garage or construction site is at or close to grade; objects close to grade are easy for current hoisting devices to reach, hoist and move. However, there is considerable room for improvement in the field of suitable apparatus or methods capable of reaching, hoisting and moving objects that reside high above grade or in a generally inaccessible area.
The prior art includes various types of lifting or hoisting devices, each of which provides certain advantages in use or construction.
The prior art includes devices for lifting and transporting heavy and awkward objects such as raw materials in metal fabrication shops. The raw materials being too heavy for conventional fork lifts, or having dimensions that make it impossible for transportation on a fork lift through narrow warehouse passageways. One such device is taught by U.S. Pat. No. 2,679,329. The device of U.S. Pat. No. 2,679,329 comprises a primary unit and a secondary unit, each having a lifting means connected to a frame wherein the frame members are all rigidly fabricated to one another. The secondary unit is to be attached to the primary unit when necessary to transport materials exceeding the length of the primary unit. Both the primary and the secondary units are to be used in conjunction with a fork lift. The fork lift is a needed addition to the device and is used for loading materials onto the units, and to tow the units after loading.
The prior art also includes a device for lifting and transporting heavy and awkward objects which comprises a disc carrier attached to a trailer to be towed by a tractor. One such device is taught by U.S. Pat. No. 2,657,938. The device of U.S. Pat. No. 2,657,938 comprises a frame constructed of tubular members rigidly attached to one another. A lifting means is provided on the frame for lifting discs and wheels. The wheels provide support for the trailer and facilitate transportation of the device. This device taught by U.S. Pat. No. 2,657,938 is designed to relocate discs from one field to another. Therefore the structural members need not necessarily be designed for easy or quick disassembly, but instead can be rigidly attached to one another.
U.S. Pat. No. 2,528,672 discloses a portable lifting device used to elevate mechanical equipment and for transporting large and bulky equipment. The portable lifting device taught by U.S. Pat. No. 2,528,672 is comprised of a unibody frame structurally enhanced for bearing large loads. Connected to the frame is a winch for hoisting and maintaining at elevation large loads for relocation. Additionally connected to the frame are wheels for support and ease of movement of the device. As evident from its structural design this device was designed to be towed, in whole, to the object to be moved.
U.S. Pat. No. 3,329,284 discloses a self-propelled marine hoist for removing boats from water and placing the boats on shore for repair and storage. The apparatus of U.S. Pat. No. 3,329,284 is described as being capable of disassembly for easy shipping and reassembly at the lifting site. Certain difficulties are described in the disassembly, reassembly process such as the need for multiple personnel on hand to disassemble and reassemble the apparatus--at least one of which being required to have experience in the disassembly/reassembly process of the apparatus. U.S. Pat. No. 3,329,284 also discloses an internal combustion engine for propelling the apparatus and power for the lifting means, and suggests that this device could transport heavy machinery or other bulky loads over land from one point to another.
One current apparatus and method for relocating heavy cumbersome objects on roof tops involves a large crane. Currently crane rental is expensive and time consuming, as is the requisite manpower associated with operating a crane.
There still exists in the art a need for a lifting or hoisting device which is easily disassembled, easily transported once disassembled, easily reassembled, and exhibits flexibility of positioning, and provides four independent lift means.